High Intensity Interval Training or HIIT for short is a form of cardio training that involves repeated short bursts of a high intensity exercise followed by a short rest. One example is going all out on a rowing machine for 30 seconds, resting for thirty seconds and repeat for 10 - 20 minutes. Studies have consistently shown this style of training to be more beneficial for fat loss and fitness than your typical steady state cardio like jogging for an hour. It is also more time effective and in my opinion more fun.

HIIT has been gaining popularity over the last few years and for good reason, but like with anything that gains popularity, it inevitably gets butchered, usually by people trying to make money.

In my classes we usually do 15 or 20 minutes of high intensity work at the end, because that is all you need, but last week I saw a gym advertising a 60 minute HIIT class. To me this just sounded ridiculous, because there is no way you can do high intensity (90%+ of maximum heart rate) for longer than 20 minutes. You simply cannot maintain that level of intensity because your body wont be able to produce energy quickly enough to enable you to keep going without thing getting messy and risking injury.

With my clients and in classes we always end our high intensity work just before we need to. This allows for better recovery and more frequent training. It would be counterproductive to beat somebody into the ground if it meant they took a week to recover. Doing slightly less work, recovering properly and training 2-3 times a week is a lot more effective than 1 body breaking session.

I wanted to prove that you cannot maintain HIIT for longer than 20 minutes without risking injury. Now I could have tested it on myself, but thankfully I have guinea pigs who are willing to do this sort of thing for me. I'd like to introduce you to Vanessa. Vanessa has been training with us for a good while, she is very fit (fitter than me), she's got some determination and likes a challenge, so was the perfect candidate to test my theory. We first needed to work out 90% of her maximum heart rate, which is (220 - her age) x 0.9. I wont tell you what her age, because it's pretty old and I don't think she'd appreciate it. For the exercise to be counted as high intensity her heart rate needed to be between 90 and 100% during the work sets so I rigged her up to a heart rate monitor.Kettlebell snatches are an excellent exercise for this type of training so we began with those and decided to do 30 seconds work, 30 seconds rest with a 12kg kettlebell.

After a short 3 minute warm up we started the test. Vanessa had to go all out with the snatches for 30 seconds, then put the kettlebell down rest for thirty seconds and repeat for as long as she could. After 16 minutes she had kept her heart rate in the 90-100% range, but her hands started to to get sore. Grip strength is usually the limiting factor with snatches because you are holding onto a lot of weight. Normally this is where the session would finish, but as she was still standing we decided to change the exercise to Hill Climbers and keep the test going. The hill climbers weren't as effective as snatches, but her heart rate was still above 90%, so it was still high intensity. Much to my dismay the 20 minute mark approached and Vanessa was still going strong, which made me wrong and I hate that, but it seemed to please her.

At 22 minutes however, things started to slow down and she struggled to complete the 30 seconds, the next set was the same. The last 7 or 8 seconds of hill climbers became slow and laboured, it was time to end the test at 23.5 minutes.

Although I was wrong by 3.5 minutes, we (the royal we) did show that there is no way you can maintain high intensity intervals for an hour.

HIIT is a great way to train and everybody (except those with a heart condition) should be doing it. Some people think it is only for people who are really fit like Vanessa, but it isn't. It's just that an untrained individuals "high intensity" might be step ups or star jumps rather than snatches and that is fine as long as you find it hard. Aim for 10 - 20 minutes 2-3 times per week, add in some brisk walks throughout the week and that is all the cardio you need.

People have a tendency to label foods as either good or bad. The low fat advocates will tell you fat is bad and the low carb posse will tell you carbohydratess are bad, but that is too much of a generalisation. We need to look at the specifics of each macronutrient (carbohydrates, fats and protein) to make an educated decision.

Today we're going to focus on carbohydrates.

Most people think of carbohydrates as bread, pasta and rice, but they include more than this and are divided into 3 catagories: sugar, starch and fiber.

Sugars are either monosaccharides (mono = one, saccharide = sugar) like glucose or fructose found in fruit, or disaccharides (di = two, saccharide = sugar) like sucrose, table sugar.Starches are polysaccharides (poly = many), which simply means there are lots of sugar molecules bound together, these are found in potatoes, bread, rice etc. You'll notice that starches are just sugar molecules bound together.

The less molecules a carbohydrate has, the quicker it is broken down to use as fuel. If you were in the Great Manchester Run this weekend, you would find a banana or sugary drink useful around the the 7k point to give you some easily digested energy to help you finish the race. If you were sat at home watching the Britain's Got Talent repeat, chances are that same banana would have just been stored as fat. Carbohydrates are used to create energy for the body to be used for movement. The quicker a carbohydrate is broken down the sooner it is available to use, but if you don't use it, it will get stored as fat with the intention of being used at a later date. As you can see banana's aren't bad, in some situations they are a good choice, but in others not so much.

If you're not doing prolonged physical activity you have little need for fast acting sugars, so you want to stick to starches and limit sugar intake. How much you need will depend on how much movement you do throughout the day. Most people will use 200 to 300 calories a day moving around (this would increase if you went to the gym or did any type of exercise), so if you weren't trying to lose fat, your carbohydrate intake should match that. If you are trying to lose some body fat, then you want to eat less carbohydrates than you need. This will force your body to breakdown your stored fat in order to fuel your activity. This can be done by either increasing your activity levels or decreasing your carbohydrate intake, or ideally a bit of both. Starches are the best option as they are released slower, so are less likely to get stored as fat and they will fill you up for longer, because they take more time to break down.

As you can see sugar and starches aren't bad and the only thing that makes one better than the other is the situation you are in. Eat your carbohydrates wisely and make sure the amount you eat matches your goals.

The third type of carbohydrate Fiber is strings of sugars, like starches, except that the bonds between the sugars cannot be broken down for energy. Fibre is found in most vegetables and is generally good for your health, but some fiber is better than others. The fiber found in vegetables and tubers (potatoes, sweet potatoes etc) are fermentable (I'm not convinced fermatable is a word, but I'm going with it), whereas the fibre found in whole grains aren't, as much.

Fermentable fiber is important for the health of our gut. We have beneficial bacteria in our gut that uses fiber for food. These beneficial bacterias are pretty useful for detoxifying harmful compounds in our food and water, they are also crucial for an effective immune system and can help prevent diabetes and other autoimmune diseases. So we want to keep these guys happy and well fed, grains won't do it, so make sure you get your fiber from fruits and veg.

Hopefully this clears up the confusion about carbohydrates. Carbohydrates aren't bad, you just need to choose the right types in the correct amounts.

Variety is the spice of life, or so they say, but it may also be the reason you aren't getting the results you want.

Everybody likes variety especially when it comes to food, a new flavour to get your taste buds tingling, but this is one of the main reasons people overeat. The first few mouthfuls of any food are always the best, that is why we can always make room for dessert even after a large meal, but it is not just sweet things we can overeat on. If you go to a buffet with a large selection of savoury foods there is a good chance you will eat more than you need, because you want to taste all the nice food, even if it is just a few mouthfuls.

I love mixed grills and some restaurants offer some huge mixed grills, served on great big platters, but I have never failed to finish one. All the different flavours from the beef, lamb, sausage, chicken, egg and if I'm lucky black pudding keep me going back until my plate is clean. Obviously these are not bad foods to be eating, but 2000 calories in one sitting will be more than I need (depending on what else I have eaten that day). If you gave me the equivalent calories in scrambled egg, another food I love, I wouldn't eat nearly as much, because I would stop when I was full, there wouldn't be any new flavour to tempt my taste buds and keep me coming back for more.

If you only ate chicken liver, sardines, eggs, sunflower seeds and kale I guarantee you would lose fat, and a decent amount of it. These 5 foods provide all the essential fats, proteins, vitamins and minerals you need, so you would be perfectly healthy eating just these foods (I'd love to take credit for working this out, but unfortunately I can't. It was a clever lady called Zoe Harcombe who did the work).

Lose lots of fat, be perfectly healthy. What's stopping you?

Boredom! After 4 weeks if you're a resilient person, but more than likely less than 2, you will be bored to death of those 5 foods and you wont be able to stick to it. However you could use a certain lack of variety to your advantage and still be able to stick to it.

Keeping things simple and a little bit boring for a few weeks could really help kick start your weight loss or get you through a plateau. If your plate just has one meat and two veg, no sauces or anything fancy, for one it is easy to monitor how much you are eating and for two the lack of new tastes will help you to stop when you are full. Have the same meal for lunch and tea each day, for a few weeks. You can eat as much as you like, but only those foods. Have variety throughout the week to make sure you are getting everything you need, but during the course of one day only eat the same 4 or 5 foods.

Wednesday: Lunch - Homemade burgers with kale, Tea - Homemade burgers with fried mushrooms and tinned tomatoesRemember it is not just calories that count, the balance of calories is just as, if not more important. We discussed that a few week ago here, but this is a sure fire way to stop you overeating.